1. Field of the Invention
The present invention relates to a process for the production of a dioxolan from an alkyl glycidyl ether, and a process for the production of a glyceryl ether from this dioxolan.
2. Description of the Prior Art
As .alpha.-monoalkyl glyceryl ethers, there have hitherto been known palmityl glyceryl ether (i.e. Chimyl alcohol) which is present in the lipids of fish, stearyl glyceryl ether (i.e. Batyl alcohol) and oleyl glyceryl ether (i.e. Serachyl alcohol). And it is known that they exhibit excellent performance as an emulsifier, particularly as a W/O type emulsified (Japanese Laid-open Patent Applications Nos. 92239/74, 12109/77, and 87612/74). Also they are known to have pharmacological activities such as stimulating effects for the formation of blood cells in the bone marror, anti-inflammatory effects and anti-tumor activities (Japanese Patent Publications Nos. 10724/74, and 18171/77). The following two methods are known for the production of these .alpha.-monoalkyl glyceryl ethers from the corresponding alcohols.
(1) An alcohol is converted into an alkylhalide, which is then reacted with a glycerol alkali metal alcoholate having hydroxyl groups protected, thereby to obtain a 4-alkoxymethyl 1,3-dioxolan, which is then hydrolyzed. The reactions are represented by the following formulae: ##STR1## (where R' is an alkyl group, etc, X is a halogen, and M is an alkali metal).
(2) An alkyl glycidyl ether is produced from an alcohol and an epihalohydrin, and it is then hydrolyzed. The reactions are represented by the following formulae. ##STR2## (where R' is as defined above, and X is a halogen).
These methods have the following drawbacks and accordingly they are not entirely satisfactory.
Namely, in the method (1), although the hydrolysis of the 4-alkoxymethyl-1,3-dioxolan to the glyceryl ether proceeds almost quantitatively, it is difficult to produce the dioxolan on an industrial scale. (i) Firstly, an alkylhalide must be prepared from an alcohol. It is, however, difficult to produce an alkylhalide containing an unsaturated bond on an industrial scale. (ii) Although the glycerol compound having the hydroxyl group protected (4-hydroxymethyl-1,3-dioxolan) can be synthesized from glycerine and a carbonyl compound in the presence of an acid catalyst, it takes a long period of time for the reaction, which is a dehydration reaction and accordingly requires a great amount of a dehydrating agent. (iii) In the reaction system for the condensation reaction of the alkylhalide and the alkali metal alcoholate of 4-hydroxymetyl-1,3-dioxolan, there exists a strong base and a part of the alkylhalide is thereby subjected to dehydrohalogenation reaction to form a terminal olefin, whereby the yield of the intended 4-alkoxymethyl-1,3-dioxolan is reduced.
With respect to the method (2), certain processes have recently been developed whereby alkyl glycidyl ethers can be produced in high yield from alcohols R'OH without necessity of isolating halohydrins (e.g. Japanese Laid-open Patent Applications Nos. 76508/79, 141708/79, 141709/79 and 141710/79). In order to obtain a glyceryl ether by the hydrolysis of the glycidyl ether, it is most effective to react the glycidyl ether with water with use of an acid catalyst. According to the results obtained from the studies by the present inventors, however, the reaction can hardly be conducted uniformly as the reaction system is a non-uniform system comprising water and oil, as shown in the comparative examples given hereinafter. Accordingly, in addition to the intended glyceryl ether, a great amount of polymers is produced as by-products as a result of the addition polymerization of the glycidyl ethers themselves. Thus, the yield of the glyceryl ether is lowered and the quality of the product is degraded. In order to obtain the glyceryl ether of high purity, a purification operation such as molecular distillation is required, and this makes it difficult to carry out the operation on an industrial scale.